Thought I'd revive this thread as I now have an actual experience with SnapNames.com to relate.
There's a particular domain name I've wanted to own for the past few years, but I missed buying it last time it became available. I saw the current registration was about to expire, so I bit the bullet and paid SnapNames.com $69 to "backorder" the domain. The domain was registered with Network Solutions, so I assumed SnapNames would be the service that would get first crack at the domain.
Today I recieved an email stating that the domain had been transferred away from Network Solutions. I checked the Whois information and found the domain had been purchased by someone two days ago. It's now "for sale" at a domain reseller for a couple thousand dollars.
So, my experience says SnapNames.com doesn't work. I paid $69 to get "first crack" at the domain the second it expired, but someone else managed to register it first. SnapNames only allows one backorder per domain name, so the person who bought it must have just registered it the old-fashioned way, through another registrar.
My two cents is that SnapNames seems to be a big waste of money. If the current registrar can't automatically grab the domain at the moment they delete it from their database, then the entire exercise seems pointless.